James Tiberius Kirk was the third Captain of the first starshipEnterprise, and Captain of the second ship to bear that name, for some time between the fourth and sixth Star Trek movies. He was also, ironically the man responsible for the scuttling of the first Enterprise over the Genesis planet.

Born in Iowa, Kirk spent at least part of his life on the colony world of Tarsus IV where he was one of nine people to survive witnessing the massacre of half the colony's population by its own governor to conserve critical supplies. However, the governor of Tarsus IV was premature in cutting back on the mouths he had to feed - a relief ship arrived days later and the colony was saved. Kirk would go on to go to Starfleet Acadamy and there beat the infamous Kobayashi Maru no-win simulation by cheating. Kirk would be posted as an Ensign to the starship Republic, and from this first posting enjoyed a rapid rise through Starfleet. Kirk was a great lover of women, but an even greater lover of his service and his ship. Family remained important to him however. After his son was killed by a Klingon, his previous professional demeanor hardened into a cold hatred of all Klingons.

Kirk is often portrayed as one of the Federation Starfleet's finest officers by the fans of Star Trek universe, and is generally agreed to be pretty awesome by all, even if his hand-to-hand combat style of Kirk-fu is often mocked. Kirk was unlike many other Starfleet captains, a man of action and risk. He personally faced down the genetic superman Khan, whereas Picard would likely have tried to negotiate and Janeway would likely have attempted to bore him to death with technobabble.

James T. Kirk was played by William Shatner in every incarnation except for the upcoming eleventh Star Trek movie.